It is shown that the stimulation spectra of Eu2+ luminescence in BaFBr : Eu2+ based imaging plates are strongly dependent on the energies of the incident charged particles and the ratios of the luminescences stimulated by two different light wave lengths, e.g. of 600 and 500 nm, indicate simply the energies. This additional feature enables us to determine the incident particle energies by the imaging plate itself, keeping all the high performances of the imaging plate intact.